Hot-rolling stand for a hot-rolling mill and for producing a flat metal product, hot-rolling mill and method for operating a hot-rolling mill

ABSTRACT

A hot-rolling stand ( 10 ) for a hot-rolling mill comprises an adjusting device ( 12 ), which is intended for receiving a pair of work rolls ( 17 ) and for positioning work rolls ( 18, 19; 20, 21 ) of the pair of work rolls ( 17 ) in relation to one another to define a roll gap. In order to create a hot-rolling stand ( 10 ) that can be adapted as flexibly as possible, the adjusting device ( 12 ) is designed to interchangeably accommodate, in the pair of work rolls ( 17 ), different roll diameter ranges by means of mutually complementary work rolls ( 18, 19; 20, 21 ).

TECHNICAL FIELD

The disclosure relates to a hot-rolling stand for a hot-rolling mill andfor producing a flat metal product, comprising an adjusting device,which is intended for receiving a pair of work rolls and for positioningwork rolls of the pair of work rolls in relation to one another todefine a roll gap. Furthermore, the invention relates to a hot-rollingmill and a method for operating a hot-rolling mill.

BACKGROUND

Rolling mills are used to form metallic starting products. Inhot-rolling mills in particular, starting products are formed from aprimary shape to an intermediate or final dimension in the hot state.For this purpose, the hot-rolling mills can be directly connected to acontinuous casting line. Typically, a hot-rolling mill for a flatproduct has an equalizing or reheating furnace for heating and/orhomogenizing the starting product to the desired forming temperature andother units. Depending on the end products to be produced, for examplethe material, the target dimension or the desired degree of deformation,such units are then combined in sequence in a line to form a rollingtrain. Typically, these are hot-rolling stands, transport sections,cooling equipment, separating equipment, heating equipment and/orsurface treatment equipment. In a hot-rolling stand, the rolled materialto be treated is formed by work rolls of a pair of work rolls, which isusually accommodated in a roll stand in combination with support rolls.Thereby, a roll diameter range of the work rolls is usually determinedwith regard to various operating parameters of the hot-rolling mill andalso parameters to be achieved for the end product to be manufactured.

JP 56313601 A shows a roll stand that discloses a change ofconfiguration from a quarto-type roll stand to a sexto-type roll standto be able to roll a more comprehensive range of thicknesses. To changethe configuration, both an intermediate set of rolls and a set of workrolls are inserted into the installation space of the set of work rolls,wherein the work rolls have a relatively small roll diameter.

SUMMARY

The disclosure is based on the object of realizing a hot-rolling standfor a hot-rolling mill, wherein the hot-rolling stand is to beadjustable as flexibly as possible to different finished products,process designs, dimensions, materials and/or quality requirementswithout having to include an additional/further set of rolls in thestand.

The object is achieved by the subject matter as in the independentclaim(s). Each of the dependent claims sets forth advantageous furtherdevelopments of the invention.

A hot-rolling stand comprises an adjusting device that is provided foraccommodating a pair of work rolls and positioning work rolls of thepair of work rolls in relation to one another while defining a roll gap.Preferably, the adjusting device of the hot-rolling stand therebycomprises a roll stand in which the pair of work rolls is mounted and inwhich the work rolls of the pair of work rolls are positioned inrelation to one another via further components of the adjusting device.The pair of work rolls consists in particular of two work rolls in theform of a lower work roll and an upper work roll, wherein, in the rollstand, each of the individual work rolls preferably is guided in anassociated guide element in the mounted state. The respective guidingelement is thereby in particular a respective chock, in which therespective work roll is rotatably mounted.

In particular, each of the work rolls of the pair of work rolls is incontact with at least one support roll in the mounted state, againstwhich the individual work roll can be supported in the course of arolling operation and the application of a corresponding forming forceto the rolled material to be formed. These support rolls are alsopreferably each guided in an associated guide element, which ispreferably also a chock.

The “adjusting device” of the hot-rolling stand in accordance with theinvention is a device by means of which the work rolls of the pair ofwork rolls can be positioned in relation to one another, if necessaryindirectly via intermediate support rolls, forming a desired roll gap.In addition to two roll stands, the adjusting device particularlypreferably comprises further components that can include a wedgeadjusting device of a lower work roll of the pair of work rolls and/or ahydraulic positioning device of an upper work roll of the pair of workrolls and/or in each case a work roll bending device of the lower and/orthe upper work roll. Thereby, the wedge adjusting device, the hydraulicpositioning device and the respective work roll bending device can eachhave further individual components if necessary.

The roll stand is designed as a hot-rolling stand for use in hotrolling, that is, for a rolling process of a rolled material at atemperature above the recrystallization temperature of a metal to beprocessed. A “roll gap” between the work rolls of the pair of work rollsrefers to a distance between the work rolls.

The adjusting device is designed to interchangeably accommodate, in thepair of work rolls, different roll diameter ranges by means of mutuallycomplementary work rolls. In other words, with the hot-rolling stand,the adjusting device is designed to accommodate work rolls of a pair ofwork rolls, wherein the work rolls can thereby be replaced in pairswhile changing the roll diameter range. The work rolls mounted in thehot-rolling stand always correspond to one another with regard to theselected roll diameter range. The selectable (work) roll diameter rangesdiffer from one another in that the diameter deviation goes(significantly) beyond the usual roll grinding.

Such a design of a hot-rolling stand has the advantage that, due to theinterchangeability in pairs of the work rolls of the pair of work rolls,the hot-rolling stand can be adjusted to the desired operatingparameters. Thus, such adjustment can take place through the suitableselection of the roll diameter range with regard to a respective productto be manufactured, a respective process control, respective dimensions,respective materials and/or respective quality requirements, such thatthe spectrum of products that can be manufactured is increased. Suchadjustment can be made more rapidly and easily without the need foradditional rolls in the stand. With regard to the rolled materialdimensions in a hot-rolling mill, the introduction of an additional setof rolls would lead to extensive further adjustments, for example to theinlet guides, the drive train, but also the adjusting device, whichwould have to be carried out during a maintenance shutdown, for example.Overall, the invention can be used to realize a flexibly adjustablehot-rolling stand, the application of which also makes it possible torealize a flexibly manageable hot-rolling mill by selecting a rolldiameter range of the interchangeable work rolls with regard to theplanned operating parameters.

This provides the possibility of accommodating different conditions andrequirements during hot rolling. Thus, with decreasing roll diameter andotherwise identical rolling conditions (inlet and outlet thickness,width, material, inlet temperature, strip speed), the system load(rolling force, rolling moment), a heat flow from the rolled materialinto the respective work roll and also the energy consumption decreasedue to the reduced forming work. On the other hand, the pressure angleis reduced as the roll diameter increases, while the inlet thickness andthe absolute reduction remain constant. The smaller the pressure angle,the lower the risk of slippage of a strip of rolled material or ofpassing problems. In addition, with a roll diameter and a correlatingdrive journal diameter, the transferable torque also increases. Byselectively changing the work rolls and thus changing the roll diameterrange, the hot-rolling stand can thus be adjusted to the productionparameters to be represented, such as the product to be manufactured, arespective process control, respective dimensions, respective materialsand/or respective quality requirements, without having to compromise onthe selection of a roll diameter of the work rolls.

The hot-rolling stand is designed such that the work rolls of the pairof work rolls can be mounted interchangeably and correspondingly to oneanother with different roll diameter ranges. Preferably, at least twodifferent roll diameter ranges can be realized for the individual workroll of the pair of work rolls. In accordance with the invention, thework rolls of the pair of work rolls are always mounted withcorresponding roll diameter ranges; that is, the currently mounted workrolls always have the same roll diameter range.

In the hot-rolling stand, the work rolls are preferably replacedlaterally and substantially perpendicularly, particularly preferablyperpendicularly, to the longitudinal extension of a throughput section.

A “roll diameter range” refers to a diameter range of the individualwork roll that is characterized by a nominal roll diameter and agrinding range. The grinding range defines a permissible diameterreduction of the respective roll over its operating time. The selectableroll diameter ranges differ from each other in that the diameterdeviation (significantly) exceeds the usual roll grinding.

According to one embodiment, the hot-rolling stand is designed as aroughing stand. In such a case, the hot-rolling stand is thereforedesigned to be used within a hot-rolling mill as a roughing stand forthe entry-side rolling of the rolled material in the hot-rolling mill.In accordance with an alternative design option, the hot-rolling standis designed as a finishing stand that is used within a hot-rolling mill,in particular for the stepped forming of the rolled material to apredetermined dimension.

In a further development, a deviation between the different rolldiameter ranges amounts to ≥6%, preferably ≥10%. A deviation between theroll diameter ranges that can be represented by replacement is thus atleast 6% between a small roll diameter range and a large roll diameterrange, but preferably at least 10%. This has the advantage that, with adeviation in such order of magnitude, the different requirements andalso different correlations between rolling parameters and rollingdiameter can be taken into account through a change.

In accordance with a further embodiment, the adjusting device comprisesas components a wedge adjusting device of a lower work roll of the pairof work rolls and/or a hydraulic positioning device of an upper workroll of the pair of work rolls and/or in each case a work roll bendingdevice of the lower and/or the upper work roll, wherein the componentsof the adjusting device in each case have a range of adjustment tointerchangeably accommodate the mutually complementary work rolls withdifferent roll diameter ranges. This makes it possible to accommodatework rolls with different roll diameter ranges in the hot-rolling stand,since the components can individually or collectively represent thestrokes required for this purpose.

It is a further design option that the hot-rolling stand is designed forreversing operation or one-way operation. In such a case, design forreversing operation means that the rolled material is fed through thehot-rolling stand several times and in a reversing manner, that is, withopposite conveying directions to one another, whereas in one-wayoperation the rolled material is fed through the hot-rolling stand onlyin one direction and only one time.

In a further development of the invention, a pass line variation whenusing the different roll diameter ranges amounts to less than +/−20 mm,preferably +/−15 mm, more preferably +/−10 mm. Thereby, the “pass line”is to be understood as a difference in height between the lower workroll of the pair of work rolls and an adjacent roll of a roll table,wherein the fluctuation of the pass line should be as low as possible,as otherwise difficulties could arise when threading the rolled materialbetween the work rolls, or a collision of the rolled material with thelower work roll could arise.

It is also an object of the disclosure to provide a hot-rolling millcomprising at least one hot-rolling stand designed according to one ormore of the aforementioned variants. Preferably, the hot-rolling mill iscomposed of a plurality of units, which may include a pre-heating unit,a roughing rolling train, an intermediate heating unit, a finishingrolling train, a transport unit, a rewinding unit and/or variousseparating units. In addition, the hot-rolling mill can have otherunits, such as scale washers, possible induction heating equipment, andthe like.

According to a preferred embodiment, a hot-rolling mill is provided witha roughing rolling train having at least one roughing stand and afinishing rolling train having at least one finishing stand, wherein atleast one roughing stand of the roughing rolling train and/or at leastone finishing stand of the finishing rolling train each is designed as ahot-rolling stand according to one or more of the aforementionedvariants. Particularly preferably, both with at least one roughing standof the roughing rolling train and in at least one finishing stand of thefinishing rolling train, work rolls of the respective pair of work rollscan be changed in pairs while changing the roll diameter range.

The disclosure also relates to a method for operating a hot-rollingmill. Thereby, at least the following method steps are carried out:

-   -   a) Checking a production sequence to be represented for        operating parameters;    -   b) Checking a currently selected roll diameter range of work        rolls of a pair of work rolls of at least one hot-rolling stand        designed according to one or more of the aforementioned        variants;    -   c) Checking whether the currently selected roll diameter range        matches the operating parameters of the production sequence to        be represented,        -   wherein, in the case to be answered in the negative, a            change of work rolls in pairs of the pair of work rolls with            a change of the roll diameter of the work rolls is carried            out at the at least one hot-rolling stand and/or a change of            the production sequence to be represented is carried out,            and wherein subsequently the check is initiated again            starting on step a),        -   while in the case to be affirmed the rolling operation is            carried out without any change.

In other words, the method initially records operating parameters of aproduction sequence to be represented by the hot-rolling mill. Theoperating parameters define the process steps required to produce atarget product from a starting product and process parameters of thehot-rolling mill and the rolled material during the process steps. Suchoperating parameters preferably include the parameters of pass reductionand operating mode. Moreover, with at least one hot-rolling standdesigned according to one or more of the aforementioned variants, acurrent roll diameter range of work rolls of a pair of work rolls ofsuch hot-rolling stand is determined. Subsequently, there is a check ofwhether the desired operating parameters can be realized with thecurrent roll diameter range of the at least one hot-rolling stand. Ifthis is the case, a rolling operation is carried out without undertakinga change. If, on the other hand, it is determined that the current rolldiameter range of the work rolls of the pair of work rolls and theoperating parameters of the production sequence to be represented do notmatch, the work rolls of the pair of work rolls are changed in pairswhile changing the roll diameter range, and/or the operating parametersof the production sequence are changed in order to match the operatingparameters and the roll diameter range of the work rolls of the at leastone hot-rolling stand. The check procedure is subsequently repeateduntil the production sequence matches the operating parameters inconjunction with the determined work roll diameter range, andsubsequently the rolling operation is initiated.

This has the advantage that the hot-rolling mill can be used for a widerange of production without having to compromise with respect tooperating parameters. Specifically, if it is determined that the desiredoperating parameters cannot be achieved or cannot be achieved optimallywith the currently mounted work rolls, then as an alternative or inaddition to changing the operating parameters, the roll diameter rangeof the pair of work rolls in the at least one hot-rolling stand can alsobe changed in order to achieve the parameters even better. Overall, thisallows the flexible use of the hot-rolling mill while at the same timereliably achieving the desired operating parameters.

According to one embodiment, when the work rolls are changed in pairs, achange is made to a smaller roll diameter range if a pass reduction of≥40%, more preferably ≥50%, ≥60% or most preferably ≥70% is detected inthe hot-rolling mill. Pass reductions of this order of magnitude usingwork rolls with a smaller roll diameter range have the advantage ofreducing the system load, the heat flow from the rolled material intothe respective roll and also the energy consumption due to the reducedforming work. A “pass reduction” is understood to mean the thicknessratio of the rolled material entering the roll gap to the rolledmaterial leaving the roll gap.

In a further development of the aforementioned embodiment, a furtherreason for changing to a smaller roll diameter range may be that anumber of passes of the single work roll is smaller than a number offully wound coils. This indicates endless or semi-endless operation ofthe hot-rolling mill, with each of which the use of work rolls with asmall roll diameter range is advantageous. The same is preferably alsocarried out if a rolled material to be rolled is rolled endlessly and,accordingly, de facto endless operation of the hot-rolling mill takesplace.

As a further alternative, when the work rolls are changed in pairs, achange is made to a smaller roll diameter range if there are no breaksin operation in rolling steps for the production of individual, fullywound coils.

It is a further design option that, when the work rolls are changed inpairs, a change is made to a larger rolling diameter range if one passof a roll stand is made for each fully wound coil. One pass of a rollstand per fully wound coil means a single operation or batch operationof the hot-rolling mill, with which the use of work rolls with a largerroll diameter range is advantageous due to the greater thicknesses ofthe rolled material. By using the larger roll diameter range, thepressure angle can be kept small, thus avoiding slippage of the rolledmaterial.

In accordance with one embodiment, the method steps are guided by asystem configurator. Thus, a higher-level control unit is provided,which carries out the method steps and can accordingly initiate andcoordinate the change of a roll diameter range of the work rolls at theat least one hot-rolling stand and/or a change of the productionsequence to be represented if the corresponding prerequisites are met.

In a further development of the aforementioned embodiment, a calculationis carried out by the system configurator taking into account geometriclimits based on support rolls currently located in the individual rollstand. The background here is that, with a roll stand, the support rollscurrently located in the roll in conjunction with the work rollscurrently located in the roll stand define the geometric conditions andthus, if necessary, stroke limitations of the adjusting device are takeninto account. For example, in the region of the ground support rolllocated in the stand, the change of the work rolls to another rolldiameter range without a simultaneous change of the support rolls may beimpossible due to the change of the stroke range. However, since achange of the support rolls is significantly more expensive than achange of the work rolls, a necessary change of the support rolls of ahot-rolling stand and the associated expense can already compensate forthe benefit of a change of the roll diameter range of the work rolls.

Alternatively or in addition to the aforementioned further development,a calculation is carried out by the system configurator taking intoaccount process parameters such as gripping conditions, rolling speed,roll rotational speed, drive rotational speed, drive torque.

It is possible to combine individual features that are apparent from theclaims, the following description of a preferred embodiment or directlyfrom the drawings. The reference of the claims to the drawings by theuse of reference signs is not intended to limit the scope of protectionof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

An advantageous embodiment of the invention, which is explained below,is shown in the drawings.

FIG. 1 shows a schematic view of a hot-rolling mill;

FIG. 2 shows a schematic illustration of a hot-rolling stand of thehot-rolling mill of FIG. 1 ;

FIG. 3 is a sectional view of the hot-rolling stand of FIG. 2 ; and

FIG. 4 is a flow chart of a method for operating the hot-rolling mill ofFIG. 1 .

DETAILED DESCRIPTION

FIG. 1 shows a schematic view of a hot-rolling mill 1 designed inaccordance with a preferred embodiment. In a production plant, thishot-rolling mill 1 can be connected in particular to an upstreamcontinuous casting plant—which is not shown further here—and comprises aroughing rolling train 2, a finishing rolling train 3, a coiler 4 andshears 5 and 6.

In a main transport direction 7 of the hot-rolling mill 1, theentry-side roughing rolling train 2, which is composed of severalroughing stands 8 arranged one behind the other, is initially followedby the shear 5, which is arranged between the roughing rolling train 2and the finishing rolling train 3 in the main transport direction 7. Thefinishing rolling train has a plurality of finishing stands 9 arrangedone behind the other, which are followed within the hot-rolling mill 1in the main transport direction 7 initially by the shear 6 and at theend by the coiler 4. For reasons of simplification, no further knowncomponents, such as scale washers, heating devices, cooling devices,etc., are shown.

FIGS. 2 and 3 show views of a hot-rolling stand 10, which canspecifically be one of the roughing stands 8 of the roughing rollingtrain 2 or one of the finishing stands 9 of the finishing rolling train3. Thereby, the hot-rolling stand 10 is designed as a quarto roll standand comprises two roll stands 11, of which only one is visible in thisview, an adjusting device 12, a pair of support rolls and a pair of workrolls 17. Thereby, the pair of support rolls consists of an uppersupport roll 13 and a lower support roll 14, each of which is rotatablyaccommodated in an associated chock 15 or 16. Thereby, the support rolls13 and 14 of the pair of support rolls form the pair of work rolls 17,which is used to form the rolled material fed to the hot-rolling stand10.

As a special feature, work rolls 18 and 19 along with 20 and 21 withdifferent roll diameter ranges can be accommodated in the hot-rollingstand 10, wherein, in FIG. 3 , the left half shows an accommodation ofwork rolls 18 and 19 with a large roll diameter range and the right halfshows an accommodation of work rolls 20 and 21 with a small rolldiameter range. Each of the currently mounted work rolls 18 and 19 or 20and 21, as the case may be, of the pair of work rolls thereby always hasthe same roll diameter range, wherein the work rolls 18 and 19 or 20 and21 are changed in pairs when the roll diameter range is changed.Thereby, a deviation between the small roll diameter range and the largeroll diameter range is ≥6%, preferably ≥10%. Thereby, the individualwork rolls 18 or 19 or 20 or 21 are each rotatably guided in acorresponding chock 22 or 23 or 24 or 25, as the case may be.

Due to the different roll diameter ranges, there are also differentstrokes H1, H2, H3, H4, which are to be represented via the adjustingdevice 12 in order to position the work rolls 18 and 19 or 20 and 21 ofthe pair of work rolls while forming a required roll gap, that is, adistance between the respective work rolls 18 and 19 or 20 and 21, asthe case may be. In order to adjust the respective stroke for realizingthe respectively required roll gap, the adjusting device 12 comprises ascomponents, in addition to the roll stands 11, a wedge adjusting device26 of the lower support roll 14 and the lower work roll 18 or 20, ahydraulic positioning device 27 of the upper support roll 13 and theupper work roll 19 or 21 along with a work roll bending device 28 or 29of each of the upper work roll 19 or 21 and the lower work roll 18 or20, as the case may be. Thereby, the wedge adjusting device 26, thehydraulic positioning device 27 and the work roll bending devices 28 and29 each have a range of adjustment in order to be able to realize thedifferent strokes for representing the interchangeable accommodation ofthe work rolls 18 and 19 or 20 and 21 with the different roll diameterranges. In addition, a roll balancer 30 is assigned to the upper supportroll 13.

In the illustration of FIG. 3 , with the small work roll diameter rangeused with the work rolls 18 and 19, an extension of the adjustablestrokes of the adjusting device 12 is visible via assigned spacers,which can be part of the hydraulic positioning device 27, or the wedgeadjusting device 26. The necessary strokes can thus be adjusted directlyvia the travel of the wedge adjusting device 26 and/or the hydraulicpositioning device 27, or alternatively in combination with spacers thatsimplify the design of the adjusting device.

Via the adjusting device 12, the respective lower work roll 18 or 20 isto be adjusted with its upper edge at the height of a desired pass line31 indicated in FIG. 2 , while the respective upper work roll 19 or 21is aligned with the lower work roll 18 or 20 to define the desired rollgap. If necessary, the roll gap is initially thereby selected to belarger for threading the rolled material and is subsequently reduced.

FIG. 2 also shows a drive of the respectively mounted work rolls 18 and19 or 20 and 21 wherein, in the view in FIG. 2 , the work rolls 18 and19 with the small roll diameter region are indicated by dashed lines.Two drive motors 32 and 33, connected in tandem, are provided to drivethe respective mounted work rolls 18 and 19 or 20 and 21 of the pair ofwork rolls. A shift coupling 45 can be provided between the drive motors32, 33. The drive motors 32 and 33 are connected on the output side to atransmission gearbox 34, which may be in the form of a manual gearbox,which transmits a drive movement of the drive motors under a geartransmission ratio to a comb roller gearbox 35, via which thetransmitted drive movement is transferred by means of spindles 36 and 37in each case to the associated mounted work roll 18 or 19 or 20 or 21.For the transfer of the drive movements, the work rolls 18 and 19 or 20and 21 have coupling sleeves 38 or 39 or 40 or 41 which are accommodatedby associated sleeves 42 and 43 of the spindles 36 and 37.

It is clear that the different roll diameters of the work rolls resultnot only in stroke movements H1, H2 of the hydraulic positioning device27 and the wedge adjusting device 26, but also in stroke movements (H3,H4) of the coupling sleeves 38, 39, 40, 41 and the work roll chocks 22,23, 24, 25, which must be compensated for by the work roll bendingdevices 28, 29. The spindles 36, 37 used for both roll diameter rangesmust be designed for a deflection resulting from the strokes.

The hot-rolling mill 1 shown in FIG. 1 is used to produce semi-finishedproducts in the form of strips, wherein, depending on the requirementsof the strip to be produced, this can be done in a single or batchoperation, with which the rolled material arrives at the hot-rollingmill 1 in predetermined length sections corresponding to a finished coiland is threaded into the individual roll stand through a roll gap presetto the target thickness of the strip.

On the other hand, production can also take place in an endlessoperation, with which the rolled material is fed through the individualroll stands as an endless strip. During initial threading, the roll gapof each participating roll stand is set to the target thickness, whereinthe first target thickness is selected to be so large that the pass canbe made without any complications in terms of process technology. Toadjust thinner strip lengths of the endless strip, a transition piece ismanufactured, which piece has a wedge-shaped thickness progression overits strip length. For finishing, the rolled material/strip is onlyseparated once by the shear 6 and wound into individual coils via thecoiler 4.

For the design of the manufacturing process, the hot-rolling mill 1 hasa system configurator 44, which is schematically indicated in FIG. 1 .Among other things, this system configurator 44 is thereby capable,during the operation of the hot-rolling mill 1, of carrying out theoperation of the hot-rolling mill 1 according to a method in accordancewith the invention, the sequence of which is indicated in the flowdiagram in FIG. 4 .

Thereby, in a step S1, operating parameters of the production sequencecurrently to be represented are determined, wherein such operatingparameters preferably comprise the parameters of pass reduction andoperating mode. Upstream, downstream or parallel thereto, which rolldiameter range of work rolls 18 and 19 or 20 and 21 of the pair of workrolls 17 of a hot-rolling stand 10 is currently implemented is alsodetermined in a step S2, wherein, with such hot-rolling stand 10, asdescribed above, it is possible to replace the work rolls 18 and 19 or20 and 21 in pairs with work rolls with a different roll diameter range.Thereby, with the hot-rolling mill 1, one or more of the roughing stands8 and/or one or more of the finishing stands 9 can be designed in thismanner with interchangeable work rolls.

In a step S3, the system configurator 44 then checks whether theoperating parameters recorded in step S1 match the respective rolldiameter range of the individual hot-rolling stand 10 determined in stepS2. If this is to be affirmed, a rolling operation is carried out in astep S4 without any change.

If, on the other hand, the result from step S3 is negative, the processproceeds to step S5 and/or step S6. Thereby, in step S5, a change ismade to the production sequence and thus to the desired operatingparameters, while in step S6, the system configurator 44 brings about amodification in the roll diameter range by changing the work rolls inpairs. Thereby, the goal of the system configurator 44 is to match theoperating parameters and the respective roll diameter range.

Thereby, in step S6, the system configurator 44 takes into accountgeometric limits due to the support rolls 13 and 14 currently located inthe individual hot-rolling stand 10, since only a corresponding strokerange can be represented via the support rolls 13 and 14 of therespective hot-rolling stand 10, and an additional replacement of thesupport rolls 13 and 14 is very costly. In addition, the systemconfigurator 44 takes into account process parameters such as grippingconditions, rolling speed, roll rotational speed, drive rotationalspeed, and the like.

The function of the invention is described using the example of athree-stand roughing rolling train 2 with a roll diameter range 18, 19of 850 mm and a roll diameter range 20, 21 of 1050 mm, respectively,which can be used in the hot-rolling mill 1 with the two operating modesof batch and endless. The permissible grinding range of both rolldiameter ranges amounts to 100 mm. The rolled material in each case is asimple carbon steel.

As a rule, the system configurator 44 assigns various general parametersto the operating modes:

Operating Strip thickness Input Strip Finished strip mode Roughing standspeed thickness Endless Small Low Small Batch Large High Medium to large

Rolled material: carbon steel, “batch” operating mode

Roll Work roll Input Output Strip rotational Roll Forming diameter:thickness thickness speed speed torque temperature 1050 mm [mm] [mm][m/s] [rpm] [kNm] [° C.] Stand 1 150 108 0.29 5.3 3950 1100 Stand 2 10875 0.6 10.9 3230 1080 Stand 3 75 45 1.0 18.2 3680 1060The absolute pass reduction amounts to 70%.

In this exemplary embodiment, it is clear that the mass flow (stripthickness times strip speed) and rolling moment are relatively high. Theforming temperatures change only slightly due to the high strip speed.The system configurator 44 checks the operating parameters (initialthickness, strip speed, roll rotational speed, roll torque and formingtemperature) that result from the intended operating mode of “batch”with the work roll diameter of 1050 mm used on the basis of thecalculation model created by itself or by a connected calculation modeland comes to the conclusion that the intended operating parameters andthe roll diameter range used are suitable and that the rolling operationcan be carried out under the planned conditions.

Rolled material: carbon steel, “endless” operating mode

Work roll Input Output Strip Roll Roll Forming diameter: thicknessthickness speed rotational torque temperature 850 mm [mm] [mm] [m/s]speed [rpm] [kNm] [° C.] Stand 1 100 53 0.19 4.3 2400 1100 Stand 2 53 250.4 9.0 1780 1000 Stand 3 25 12 0.8 18.0 1115 941The absolute pass reduction amounts to 88%.

In this exemplary embodiment, it is clear that the mass flow and rollingmoment are relatively low, specifically 22% of the comparative value forthe batch mode. As a result, the strip temperature changes significantlymore, by an amount of 159° C. The system configurator 44 checks theoperating parameters (initial thickness, strip speed, roll rotationalspeed, rolling torque and forming temperature) that result from theintended operating mode of “endless” with the work roll diameter of 850mm used on the basis of the calculation model created by itself or by aconnected calculation model and comes to the conclusion that theintended operating parameters and the roll diameter range used aresuitable and that the rolling operation can be carried out under theplanned conditions. Depending on the design case, it can be suggested bythe system configurator 44 to roll with a modified shift stage of thetransmission gearbox 34 or with only one drive motor 33 in order torealize the lower speeds and torques with optimum utilization of themotor.

If, in the same exemplary embodiment, a ∘ 1050 mm roll were used in thefirst pass, the comparable rotational speed would be 3.45 and would puta strain on the motor design. At the same time, the heat transfer wouldcause the forming temperature to drop even further, such that inunfavorable cases undesirable microstructural changes could occur. Thesystem configurator 44 would come to the conclusion that either theintended rolling program is to be adjusted or a smaller roll diameterrange is to be used to improve the unfavorable operating conditions.

The two sample calculations shown are designed for a standard product.Due to the variance with regard to the alloy, temperature range, rolledmaterial width and input and output thickness, there are significantlylarger spreads that must be taken into account by the design andcalculations of the system configurator.

By means of the hot-rolling stand design in accordance with thedisclosure, a hot-rolling mill, which can be flexibly adjusted todifferent finished products, process designs, dimensions, materialsand/or quality requirements, can be realized.

LIST OF REFERENCE SIGNS

-   -   1 Hot-rolling mill    -   2 Roughing rolling train    -   3 Finishing rolling train    -   4 Coiler    -   5 Shear    -   6 Shear    -   7 Main transport direction    -   8 Roughing stand    -   9 Finishing roll stand    -   10 Hot-rolling stand    -   11 Roll stands    -   12 Adjusting device    -   13 Upper support roll    -   14 Lower support roll    -   15 Chock    -   16 Chock    -   17 Pair of work rolls    -   18 Lower work roll    -   19 Upper work roll    -   20 Lower work roll    -   21 Upper work roll    -   22 Chock    -   23 Chock    -   24 Chock    -   25 Chock    -   26 Wedge adjusting device    -   27 Hydraulic positioning device    -   28 Work roll bending device    -   29 Work roll bending device    -   30 Roller balancer    -   31 Pass line    -   32 Drive motor    -   33 Drive motor    -   34 Transmission gearbox    -   35 Comb roller gearbox    -   36 Spindle    -   37 Spindle    -   38 Coupling sleeve    -   39 Coupling sleeve    -   40 Coupling sleeve    -   41 Coupling sleeve    -   42 Sleeve    -   43 Sleeve    -   44 System configurator    -   45 Shift coupling    -   H1 Stroke of wedge adjusting device    -   H2 Stroke of hydraulic positioning device    -   H3 Stroke of upper work roll bending device/coupling sleeve    -   H4 Stroke of lower work roll bending device/coupling sleeve    -   S1 to S6 Individual steps

1.-16. (canceled)
 17. A hot-rolling stand (10) for a hot-rolling mill(1) and for producing a flat metal product, comprising: an adjustingdevice (12) that is provided for accommodating a pair of work rolls (17)and for positioning work rolls (18, 19; 20, 21) of the pair of workrolls (17) in relation to one another to define a roll gap, wherein theadjusting device (12) is designed to interchangeably accommodate, in thepair of work rolls (17), different roll diameter ranges of mutuallycomplementary work rolls (18, 19; 20, 21), wherein a deviation betweenthe different roll diameter ranges amounts to ≥6%, and wherein a passline variation when using the different roll diameter ranges amounts toless than +/−20 mm.
 18. The hot-rolling stand (10) according to claim17, wherein the hot-rolling stand (10) is a roughing stand.
 19. Thehot-rolling stand (10) according to claim 17, wherein the hot-rollingstand (10) is a finishing stand.
 20. The hot-rolling stand (10)according claim 17, wherein the deviation between the different rolldiameter ranges amounts to ≥10%.
 21. The hot-rolling stand (10)according to claim 17, wherein the adjusting device (12) comprises ascomponents a wedge adjusting device (26) of a lower work roll (18; 20)of the pair of work rolls (17) and/or a hydraulic positioning device(27) of an upper work roll (19; 21) of the pair of work rolls (17)and/or in each case a work roll bending device (28, 29) of the lower(18; 20) and/or of the upper work roll (19; 21), wherein the componentsof the adjusting device (12) in each case have a corresponding range ofadjustment to interchangeably accommodate the different roll diameterranges of the pair of work rolls (17) with the mutually correspondingwork rolls (18, 19; 20, 21).
 22. The hot-rolling stand (10) according toclaim 17, wherein the hot-rolling stand (10) supports a reversingoperation or a one-way operation.
 23. The hot-rolling stand (10)according claim 17, wherein the pass line variation amounts to less than+/−10 mm.
 24. A hot-rolling mill (1) comprising at least one hot-rollingstand (10) according to claim
 17. 25. The hot-rolling mill (1) accordingto claim 24, wherein a roughing rolling train (2) with at least oneroughing stand (8) and a finishing rolling train (3) with at least onefinishing stand (9) are provided, wherein the at least one roughingstand (8) of the roughing rolling train (2) and/or the at least onefinishing stand (9) of the finishing rolling train (3) each is designedas the hot-rolling stand (10) according to claim
 17. 26. A method foroperating a hot-rolling mill (1), comprising the following method steps:a) checking a production sequence for operating parameters, theoperating parameters including a pass reduction and an operating mode;b) checking a currently selected roll diameter range of work rolls (18,19; 20, 21) of a pair of work rolls (17) of at least one hot-rollingstand (10) designed according to claim 17; c) checking whether thecurrently selected roll diameter range matches the operating parametersof the production sequence, wherein, if the currently selected rolldiameter range does not match the operating parameters of the productionsequence, a change of work rolls (18, 19; 20, 21) in pairs of the pairof work rolls (17) with a change of the roll diameter range of the workrolls (18, 19; 20, 21) is carried out at the at least one hot-rollingstand (10) and/or a change of the production sequence is carried out,and wherein subsequently the method is initiated again with step a), andwherein, if the currently selected roll diameter range does match theoperating parameters of the production sequence, the rolling operationis carried out without any change.
 27. The method according to claim 26,wherein, when the work rolls (18, 19; 20, 21) are changed in pairs, achange is made to a smaller roll diameter range if a pass reduction of≥40% is detected in the hot-rolling mill (1).
 28. The method accordingto claim 26, wherein, when the work rolls (18, 19; 20, 21) are changedin pairs, a change is made to a smaller roll diameter range if there areno breaks in operation in rolling steps for the production ofindividual, fully wound coils.
 29. The method according to claim 26,wherein, when the work rolls (18, 19; 20, 21) are changed in pairs, achange is made to a larger roll diameter range if one pass of a rollstand is made for each fully wound coil.
 30. The method according toclaim 26, wherein the method steps are guided by a system configurator(44).
 31. The method according to claim 30, wherein a calculation iscarried out by the system configurator (44) taking into accountgeometric limits based on support rolls (13, 14) currently located inthe at least one hot-rolling stand.
 32. The method according to claim30, wherein a calculation is carried out by the system configurator (44)taking into account process parameters selected from the groupconsisting of gripping conditions, rolling speed, roll rotational speed,drive rotational speed, and drive torque.